Imaging applications such as those involving cameras, video cameras, microscopes and telescopes have generally been limited in their ability to collect light and to process light to generate images having significant depth of field. For example, most imaging devices do not record most of the information about the distribution of light entering the device, and are limited in their ability to generate focused images with a significant depth of field. Conventional cameras such as digital still cameras and video cameras do not record most of the information about the light distribution entering from the world. In these devices, collected light is often not amenable to manipulation for a variety of approaches, such as for focusing at different depths (distances from the imaging device), correcting for lens aberrations or manipulating the viewing position.
The general inability to generate images with significant depth of field applies to both still and video imaging applications. For still-imaging applications, typical imaging devices capturing a particular scene generally focus upon a subject or object in the scene, with other parts of the scene left out of focus. Similar problems prevail for video-imaging applications, with a collection of images used in video applications failing to capture scenes in focus.
One general approach to solving this problem has been the development of integrated light field cameras, which detect the light traveling each ray flowing inside the body of a conventional camera (the “light field” flowing inside the camera body). For example, the plenoptic camera utilizes a microlens array in front of the sensor in order to capture not just how much light accumulates at each spatial location on the imaging plane, but how much light arrives from each direction. Processing the recorded light rays in different ways allows, for example, computational refocusing of final photographs, or computational extension of the depth of field.
As many imaging applications suffer from aberrations with equipment (e.g., lenses) used to collect light, correcting for these aberrations is desirable and often necessary to generate high quality images. Such aberrations may include, for example, spherical aberration, chromatic aberration, distortion, curvature of the light field, oblique astigmatism and coma. Correction for aberrations has historically involved the use of corrective optics that tend to add bulk, expense and weight to imaging devices. In some applications benefiting from small-scale optics, such as camera phones and security cameras, the physical limitations associated with the applications make it undesirable to include additional optics. Moreover, as the number of photosensors used to collect image data increases, and as the arrangement and processing of data from the same becomes increasingly important, aberration and other conditions that raise issue with the creation of images can significantly hinder the ability to create accurate images. Aberrations can particularly inhibit the ability to create accurate images focused at different depths.
Difficulties associated with the above have presented challenges to imaging applications, including those involving the collection and processing of digital light data for digital imaging.